Automatic bucket positioner



April 14, 1970 J. T. GRAY AUTOMATIC BUCKET POSITIONER 2 Sheets-Sheet 1 Filed 06%.. 24, 1968 INVENTOR. c/dmas' I 61x7 ATTORNEY I April 14, 1970 J. T. GRAY 4 3,506,149

' AUTOMATIC BUCKET POSITIONER Filed Oct. 24, 1968 I z Sheets-Sheet 2 COMPRESSE AIR INVENTOR. 7 BY (fa/mes Jam ATTORNEY United States Patent 3,506,149 AUTOMATIC BUCKET POSITIONER James T. Gray, Painesville, Ohio, assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Filed Oct. 24, 1968, Ser. No. 770,224 Int. Cl. E02f 3/70, 3/84 US. Cl. 214-764 3 Claims ABSTRACT OF THE DISCLOSURE This invention pertains to a front end loader vehicle of the type having a material handling bucket supported for pivotal movement about a transverse axis by the forward end of a boom. In vehicles of this type, usually some form of hydraulic means is provided for tilting the bucket about its pivotal connection with the boom to cause the bucket to be located with its cutting edge in engagement with the ground when in a dig position and rolled back for maintaining the material within the bucket when being transported to a dumping location. Also, in most cases, the vehicle is equipped with a mechanism for automatically closing off fluid flow to the hydraulic cylinder when the bucket reaches either of the aforementioned positions.

This invention concerns a mechanism of the type described above which is simple in design, inexpensive to manufacture and permits quick adjustment to be made thereto when in the field so as to vary the position where the bucket is to stop. More specifically, the mechanism made according to the invention is mountable on a hydraulic cylinder having relatively movable piston and cylinder members and employs a flexible cable, one end of which is continuously biased in a direction away from the outer end of the piston member. The other end of the cable is attached to the piston member and is movable therewith causing an extension of the cable when the hydraulic cylinder is expanded. A cam is secured to the cable at a point along the length thereof and is adapted to activate a control circuit when the bucket reaches a predetermined position relative to the boom. The control circuit in turn serves to close a valve which supplies pressurized fluid to the hydraulic cylinder.

The objects of the present invention are to provide a control mechanism for a hydraulic cylinder that serves to automatically discontinue fluid flow to the hydraulic cylinder when the latter is expanded or contracted to a predetermined length; to provide a bucket positioner for a front end loader vehicle that includes mechanical means for activating a control circuit which in turn serves to close a valve supplying pressurized fluid to a hydraulic cylinder connected to the bucket; to provide a boom supported bucket that is movable by a hydraulic cylinder having automatic means for positioning the bucket in a dig position and a carry position; to provide a control system which serves to discontinue flow of pressurized fluid to a hydraulic cylinder when the latter attains a predetermined length and includes a prepositioned cam movable in response to movement of the piston member and serving to provide a signal upon which fluid flow to 3,506,149 Patented Apr. 14, 1970 the hydraulic cylinder is terminated; and to provide a mechanical device which can be mounted on a hydraulic cylinder and serves to interrupt fluid flow to the hydraulic cylinder when the piston attains a predetermined position relative to the cylinder.

Other objects of the present invention will be apparent from the following detailed description when taken with the drawings in which;

FIGURE 1 is an elevation view showing a front end loader having a hydraulic cylinder which controls movement of a bucket and is equipped with a control mechanism made in accordance with the invention;

FIGURE is an enlaged view of the hydraulic cylinder shown in FIGURE 1 and illustrates the detailed construction of the control mechanism mounted on the cylinder for controlling movement thereof;

FIGURE 3 is a further enlarged view taken on line 33 of FIGURE 2;

FIGURE 4 is an enlarged cross sectional view taken on line 4-4 of FIGURE 2;

FIGURE 5 is an enlarged view showing in detail the construction of the cam associated with the control mechanism of FIGURE 2;

FIGURE 6 is a schematic diagram showing the control mechanism of FIGURES l5 incorporated with a system that supplies pressurized fluid to the opposite ends of the hydraulic cylinder, and

FIGURE 7 shows a modified form of the control mechanism of FIGURES 2 through 5.

Referring to FIGURE 1 of the drawings, a rubber-tired front end loader 10 is shown, the front end of which is equipped with a lift arm or boom 12 that is connected to the vehicle by a pivotal connection 14. A lift cylinder 16 pivotally connected between the boom and vehicle serves to move the boom 12 about the pivotal connection 14 between the full line position and the phantom line position. The lower or forward end of the boom 12 carries a material handling bucket 18 for movement about a pivotal connection 20 with the bucket movement being under the control of a tilt linkage which extends between the vehicle and bucket, and includes pivotally interconnected members consisting of a link member 22, a reversing lever 24, and a hydraulic tilt cylinder 25 having relatively movable cylinder and piston members 27 and 28, respectively. In the full line position shown, the bucket 18 is in a dig position and by contracting the hydraulic cylinder 25, the bucket 18 is adapted to roll back to the carry position shown in phantom lines.

More specifically and with reference to FIGURE 6, a hydraulic control system 29 for actuating the tilt cylinder 25 is shown schematically and comprises a directional control valve 30, an engine driven pump 32 and a reservoir 34. The pump 32 draws fluid from the reservoir 34 through a line 36 and is connected tothe control valve 30 by a line 38. The control valve 30 has the usual spool valve 31 having three positions, two of which are operating positions, at which time pressurized fluid is directed through a line 40 or line 42 to one end or the other of the hydraulic cylinder 25 and also a closed position at which time fluid flow to the cylinder 25 is terminated and the fluid is recirculated back to the reservoir 34 through line 44. It will be noted that one end of the spool valve 31 is shown including an axially spaced annular groove 46 which serves to accommodate a spring biased ball 48 for holding the spool valve 31 when the latter is in one of the operating positions as will be described hereinafter. Springs 50 and 52 serve to bias the spool valve 31 to a neutral or closed position.

The spool valve 31 is movable through a lever 54, the lower end of which is pivotally connected to an ear 56 integrally formed with the spool valve 31. An intermediate portion of the lever 54 is pivoted at a point 58 to a support base 60 so the lever 54 can be moved between the three positions indicated by the letters D, N, and R, which respectively identify the Dump, Neutral, and Rollback positions for the bucket. Thus, as seen in FIGURE 1, the bucket 18 is located in the dig position and once it is loaded with material and it is desired to move the bucket 18 to the carry position, the lever 54 is placed in the operating position designated by the letter R causing the spool valve 31 to be detented in position by the ball 48 and be located so as to supply pressurized fluid through the line 40 to the cylinder end of the hydraulic tilt cylinder while simultaneously venting the piston rod end through the line 42 which will then be connected with the line 44 to reservoir 34.

As alluded to above, the control valve is provided with a detent arrangement which serves to hold or latch the spool valve 31 in place so that fluid continuously flows to the hydraulic cylinder 25 without requiring the operator to maintain manual pressure on the lever 54. It should be apparent, however, that with this type of system it is important to return the lever 54 to the neutral position N so that spool valve 31 will ciose off fluid flow to the tilt cylinder 25 when the bucket rotates to the carry position. In order to realize this function automatically, the tilt cylinder 25 is provided with a control mechanism shown in FIGURE 2 which comprises an elongated two-part tubular member 72, the rear end of which is closed by a cap 74 and is fastened to the cylinder member 27 by a pair of bolts 76. The front end of the tubular member 72 is also fastened to the cylinder member 27 by bolts 73 and is closed by a bracket having an aperture formed therein which receives without interference a flexible cable 82, the forward end of which is pivotally connected to the piston member 28 at a point coincidental with the latters pivot connection with the bucket 18. The rear end of the cable 82 is fixed to a plug 84 that is received within a retainer member 86 that is slidably supported within the rear portion of the tubular member 72. A coil spring 88 has one end thereof seated against a spacer Washer 90 that interconnects the forward and rearward portions of the tubular member 72, while the other end of the spring 88 biases the retainer member 86 toward the rear of the cylinder member 27. As seen in FIGURE 4, the forward portion of the tubular member 72 is generally rectangular in cross section and serves as a guide for a pair of identical cams 92 and 93, each of which is secured to the cable 82 by a set screw 94 as seen in FIGURE 5. Cam 92 serves as a dig position cam, while cam 93 serves as a roll-back position cam. Each of the cams 92, 93 is adapted to close a microswitch 96 which is located within a housing 98 secured to and above the tubular member 72. As seen in FIGURE 5, the microswitch 96 includes the usual plunger 100 having a roller 102which is located within an opening 104 formed in the top wall of the tubular member 72. Accordingly, it will be understood that when one of the cams engages the roller 102, the plunger is moved upwardly so as to close the microswitch 96.

As seen in FIGURE 6, the microswitch 96 forms part of an electrical circuit which includes a solenoid operated spring closed air valve 106 which is connected between a source 108 of compressed air and an actuator 110 located adjacent to the lever 54 and also mounted on the support base 60. One side of the microswitch 96 is connected to the valve 106 by a conductor 111, while the other side is connected by conductor 112 to a source 114 of electric power, such as a battery. Therefore, when the microswitch 96 is closed, the solenoid valve 106 is energized causing the valve to move toward the left as viewed in the drawing so as to connect lines 116 and 118 and permit the compressed air to be supplied to the base end of the actuator 110 and cause a spring biased plunger 120 to be extended outwardly into engagement with the lever 54 and cause the latter to rotate from the R position to the N position in a counter-clockwise direction about its pivotal support.

4 OPERATION The operation of the invention as described above is as follows. Assuming the bucket 18 is located in a dig position shown in full lines in FIGURE 1, the control valve 30 would be in a closed position and, accordingly, the lever 54 would be located in the position indicated by the letter N. When the bucket 18 has been loaded, the operator will then move the lever 54 to the R or roll-back position at which time the spool valve will be locked in position by the ball 48 and pressurized fluid is directed through line 42 to the piston rod end of the tilt cylinder 25 while the cylinder end is being vented through line 40. This causes the hydraulic cylinder 25 to contract to the carry position of FIGURE 2 and permits the spring 88 of the control mechanism 70 to draw the cable 82 into the tubular member 72. This action continues until the cam 93 engages the roller 102 of the microswitch 96 which in turn energizes the electric circuit controlling the solenoid operated valve 106 so that compressed air is directed to the actuator 110. As a result, the plunger 120 engages the lever 54 and forces the spool valve 31 to be moved in a rightward direction so the ball is urged out of its holding position in relation to groove 46 and the spool valve 31 together with lever 54 return to the N position. The boom 12 can then be raised slightly by the lift cylinder 16 and the material within the bucket 18 can be hauled to a dumping area which may require the boom 12 to be raised further to the phantom line position shown in FIGURE 1. The load is dumped out of the bucket 18 by having the lever 54 manually held in a D position causing the tilt cylinder 25 to expand until the piston member 28 reaches the dump position of FIGURE 2. In so doing, both cams 92 and 93 move forwardly of the microswitch 96 so when the lever is placed in the R position, the piston member 28 will automatically stop at the dig position of FIGURE 2 when cam 92 engages the microswitch 96. As aforementioned, each of the earns 92, 93 is secured to the cable 82 through a set screw 94 so that position adjustment of the cam along the cable can be made very quickly. In this regard and as seen in FIGURE 4, it will be noted that the lower end of the tubular member 72 is formed with an elongated slot 121 which registers with the set screws of the cams 92, 93 and permits a screwdriver to have access thereto. Thus, by loosening the set screw 94, the cam can be moved along the cable 82 axially within the tubular member 72 so as to permit the roller 102 of the microswitch 96 to be engaged at a predetermined position of the piston member 28. In order to determine the proper location of the cam on the flexible cable 82, the operator need merely place the bucket 18 in the position desired by operating the tilt cylinder 25. This position of the bucket 18 is maintained while one of the earns 92, 93 is then placed in engagement with the roller 162 of the microswitch 96. As should be apparent, thereafter whenever the cam engages the roller 102, the bucket 18 will stop in the predetermined position.

A modified form of the control mechanism is shown in FIGURE 7 and identified by the numeral 122. The principal difference in this mechanism 122 over the abovedescribed mechanism 70 is that the cams 124 and 126 are adjustably supported by a rigid rod 128 which in turn is integrally formed with a disk member 130 that is se cured to one end or" the flexible cable 82'. As in the case of the aforedescribed control mechanism 70, the opposite end of the cable 82' is intended to be connected to the eye portion of the piston member 28 which is reciprocably supported within the cylinder member 27'. A coil spring 88 is located in the forward end of the tubular member 72' and serves the same function as the coil spring 88 incorporated with the prior described mechanism. It should be apparent that the control mechanism 122 functions the same as the control mechanism 70 of FIGURE 2 and each cam 124, 126 is similarly adjustable aiong the god by a set screw 132 and serves to close the microswitch Various changes and modifications can be made in this construction without departing from the spirit of the invention. Such changes and modifications are contemplated by the inventor and he does not wish to be limited except by the scope of the appended claims.

I claim:

1. A front end loader vehicle having a boom pivoted at one end to the vehicle for vertical adjustment, a bucket pivoted at the other end of the boom, a double-acting hydraulic cylinder having relatively movable piston and cylinder members connected to said bucket for tilting the latter about said boom, a valve mounted on said vehicle and having an operating position for directing pressurized hydraulic fluid to said hydraulic cylinder for tilting said bucket and having a closed position wherein fluid flow to the hydraulic cylinder is discontinued, said valve including detent means for latching said valve in place when the latter is moved to either of the operating positions, spring means biasing the valve to the closed position, a control mechanism for releasing said detent means to permit the spring means to return the valve from the operating position to the closed position when the bucket reaches a predetermined position relative to the boom, said control mechanism comprising a tubular member mounted on the cylinder member along an axis substantially parallel to the longitudinal axis of the cylinder member, a flexible cable having one end connected to the outer end of the piston member, a retainer member slidably housed within the tubular member, the other end of said cable connected to said retainer member, a spring located in the tubular member for biasing the retainer member .in a direction away from the outer end of the piston member and causing said cable to be drawn into said tubular member when the hydraulic cylinder is contracted, a cam located in said tubular member and movable with said cable in response to movement of said piston member, an actuator supported adjacent the valve, and means on the cylinder member engageable by said cam and operatively connected to said actuator for activating the latter whereby said valve is moved from said operating position to the closed position.

2. A front end loader vehicle having a boom pivoted at one end to the vehicle for vertical adjustment, a bucket pivoted at the other end of the boom, a double-acting hydraulic cylinder having relatively movable piston and cylinder members connected to said bucket for tilting the latter about said boom, a valve mounted on said vehicle and having an operating position for directing pressurized hydraulic fluid to said hydraulic cylinder for tilting said bucket and having a closed position wherein fluid flow to the hydraulic cylinder is discontinued, said valve including detent means for latching said valve in place when the latter is moved to either of the operating positions, spring means biasing the valve to the closed position, a control mechanism for releasing said detent means to permit the spring means to return the valve from the operating position to the closed position when the bucket reaches a predetermined position relative to the boom, said control mechanism comprising an elongated tubular member mounted on the cylinder member along an axis substantially parallel to the longitudinal axis of the cylinder member, a flexible cable having one end pivotally connected to the outer end of the piston member, a retainer member slidably housed within the tubular member with the other end of said cable connected to said retainer member, a spring located in the tubular member for biasing the retainer member in a direction away from the outer end of the piston member and causing said cable to be drawn into said tubular member when the hydraulic cylinder is contracted, a cam secured to said cable at a predetermined point and movable therewith in response to movement of said piston member, an actuator supported adjacent the valve, and means on the cylinder member engageable by said cam and operatively connected to said actuator for activating the latter whereby said valve is moved from said operating position to the closed position.

3. A front end loader vehicle having a boom pivoted at one end to the vehicle for vertical adjustment, a bucket pivoted at the other end of the boom, a double-acting hydraulic cylinder having relatively movable piston and cylinder members connected to said bucket for tilting the latter about said boom, a valve mounted on said vehicle and having an operating position for directing pressurized hydraulic fluid to said hydraulic cylinder for tilting said bucket and having a closed position wherein fluid flow to the hydraulic cylinder is discontinued, said valve includ ing detent means for latching said valve in place when the latter is moved to either of the operating positions, spring means biasing the valve to the closed position, a control mechanism for releasing said detent means to permit the spring means to return the valve from the operating position to the closed position when the bucket reaches a predetermined position relative to the boom, said control mechanism comprising an elongated tubular member mounted on the cylinder member along an axis substantially parallel to the longitudinal axis of the cylinder member, a flexible cable having one end pivotally connected to the outer end of the piston member, a retainer member slidably housed within the tubular member with the other end of said cable connected to said retainer member, a spring located in the tubular member for biasing the retainer member in a direction away from the outer end of the piston member and causing said cable to be drawn into said tubular member when the hydraulic cylinder is contracted, a cam secured to said cable at a predetermined point and movable therewith in response to movement of said piston member, an air-operated actuator having a spring biased plunger supported adjacent the valve, a source of pressurized air for activating said actuator so the plunger moves the control valve from said operating position to the closed position, an electric circuit including a solenoid-operated air valve which when energized connects said source of pressurized air with said actuator, and a switch in said electric circuit engageable by said cam for energizing said solenoid-operated air valve.

References Cited UNITED STATES PATENTS 3,197,051 7/1965 Thickpenny 214764 HUGO O. SCHULZ, Primary Examiner US. Cl. X.R. 214769 

